In an advantageous embodiment of the subject of the invention, the low-pressure accumulation chamber is supplied with fuel by means of the fuel pressure in the fuel injection valve. In this case, a high-pressure valve embodied as a 3/2-port directional-control valve is disposed between the high-pressure accumulation chamber that furnishes the fuel with injection pressure, the fuel injection valve, and the low-pressure accumulation chamber. In a first position, the high-pressure valve connects the pressure chamber embodied in the valve body to the low-pressure accumulation chamber while the connection to the high-pressure accumulation chamber is closed off. In a second position of the high-pressure valve, the high-pressure accumulation chamber is connected to the pressure chamber of the fuel injection valve while the connection to the low-pressure accumulation chamber is closed off. During an injection, the full injection pressure of the high-pressure accumulation chamber prevails in the pressure chamber, i.e. the high-pressure valve is disposed in its second position. If the injection is to be terminated, the high-pressure valve switches and the highly pressurized fuel in the pressure chamber is pressure-relieved into the low-pressure accumulation chamber. By means of this, a fuel pressure is built up there, which is kept to a predetermined level by means of a pressure-holding valve. In this way, a predetermined fuel pressure level can be maintained in the low-pressure accumulation chamber without requiring a separate pressure source, for example in the form of an additional fuel pump.
In another advantageous embodiment of the subject of the invention, a control valve can feed the pressure of the low-pressure accumulation chamber into the control chamber or the control chamber can be pressure-relieved into a fuel tank. Because of the relatively low pressure in the low-pressure accumulation chamber, the control valve that controls the control chamber can be embodied as a low-pressure valve, which is much less costly than a control valve for very high fuel pressures. It is also sufficient if all of the lines from the low-pressure accumulation chamber are merely designed to function at this low pressure. In the same way, the control chamber and the piston guided in it can be produced in a correspondingly inexpensive manner.
In another advantageous embodiment of the subject of the invention, a pressure-holding valve is disposed in the leakage fuel line that can connect the low-pressure valve to the control chamber. In this manner, the control chamber is always kept at a certain fuel pressure, but one that is lower than the pressure in the low-pressure accumulation chamber. This residual pressure in the control chamber can function as a so-called oil spring, which continuously exerts a closing force on the corresponding valve needle by means of the hydraulic force on the piston. This permits the elimination of a closing spring, which is normally required to continuously exert a closing force on the valve needle that is connected to the piston.